Eucalyptus Shallow Root Danger

Impressive and Aggressive Eucalyptus Roots

• The roots of eucalyptus trees can reach over 100 feet from the trunk. The trees have a tall, upright growth habit and the roots serve to anchor the top-heavy trees in high winds. They also help the tree to absorb all the available moisture in an area, giving them an unusually high degree of drought tolerance. The top 12 inches of soil around eucalyptus trees tends to be a solid mass of roots that makes life difficult for other plants and allows the the trees to grow into extensive groves.

Hostility Toward Other Plants

• The physical crowding of the soil around eucalyptus trees with roots limits the growth of other plants through competition for moisture and nutrients. Eucalyptus are evergreens and the dense shade created by the canopy only compounds the problem. However, eucalyptus roots are also known to secrete chemicals in the soil that directly inhibit the growth of other species, a phenomenon called allelopathy. Because the soil around eucalyptus is so inhospitable to other plants, it is best to grow them on their own and utilize the natural mulch of the fallen leaves as a groundcover rather than attempt to establish understory plantings.

Danger to Structures

• Eucalyptus roots actively seek out any source of available water as they travel through the soil, making them especially dangerous to septic systems, sewer lines and water mains. The rootlets can get inside tiny spaces and then quickly expand if they find water, causing pipes to crack and eventually clogging and destroying entire networks of underground piping. Where trees grow near driveways, sidewalks, patios and foundations, the expansion of the roots can lift the paved surfaces, causing cracks, uneven pavement and other costly damage.

Managing Eucalyptus

• Planting the trees an adequate distance from other plantings and structures is the first consideration when planning to grow eucalyptus. Plant them two-thirds of their mature height from any structure to ensure the roots do not cause damage. The trees can also be contained by growing them in large pots or planters, which they tolerate, though their growth will be stunted. Eucalyptus will also tolerate being cut to the ground every two or three years, a practice called coppicing, which prevents their roots from reaching the epic proportions of which they are capable.